This blog contains minor spoilers for episode one, season four of Downton Abbey.
In American television, where repeats and syndication are a more regular feature of the schedules than in Britain, the formula "all new episode" was developed to help viewers negotiate between the reruns. In the current UK season, there's another helpful clue that this is fresh material: familiar characters have vanished.
Except for the presence of Dennis Waterman, next week's edition of New Tricks (Tuesday, 9pm, BBC1) could even carry the tagline "all new cast". With Nicholas Lyndhust and Denis Lawson having already replaced Alun Armstrong and James Bolam, Amanda Redman left this week, to be succeeded by Tamsin Outhwaite, with the result that only 25% of the original acting quartet remains.